We find that student leadership is very successful for a FIRST robotics team. Not only does it teach students responsibility, but adds a sense of authority to the "leading" students.

Here is how we on 256 set up things:

-We have 1 entire team leader, the captain, leader, president, etc. (yours truly)
-Each "subgroup" has a leader. Note: The team leader can be a leader of a subgroup, but also shares the responsibilities of every other group.

The subgroup-leads report to the team leader, and everyone else reports to their respective sub-group lead.